Computer is a device that manipulates records according to a list of commands. The first procedure that resemble recent computers date to the mid-20th century (around 1940 - 1945), although the computer idea and various machines similar to computers exist earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern private computers. Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a portion of the space. Today, straightforward computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the in sequence Age and are what most citizens think of as "a computer"; however, the most common form of computer in use today is the entrenched computer. Embedded computers are small, simple devices that are used to control other devices ? for example, they may be found in machines ranging from combatant aircraft to industrial robots, digital cameras, and junior toys.

The capacity to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The cathedral?Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in standard, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.

It is difficult to recognize any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. Originally, the term "computer" referred to a person who performed arithmetical calculations (a human computer), often with the aid of a mechanical calculating device.